package jingle

import (
	"errors"
	"fmt"
	"strconv"
	"strings"

	"github.com/pion/webrtc/v4"
)

// strips the "candidate:" prefix so candidateFromSDP gets the same shape
// it does on SDP import
func pionToCandidate(c *webrtc.ICECandidate) (*Candidate, error) {
	if c == nil {
		return nil, errors.New("nil ICECandidate")
	}
	init := c.ToJSON()
	body := init.Candidate
	body = strings.TrimPrefix(body, "candidate:")
	cand, err := candidateFromSDP(body)
	if err != nil {
		return nil, err
	}
	if cand == nil {
		return nil, fmt.Errorf("unrecognised pion candidate %q", init.Candidate)
	}
	return cand, nil
}

// fills SDPMid and parsed SDPMLineIndex when mid is numeric
func candidateToPionInit(c *Candidate, mid string) (webrtc.ICECandidateInit, error) {
	sdpBody, err := candidateToSDP(c)
	if err != nil {
		return webrtc.ICECandidateInit{}, err
	}
	init := webrtc.ICECandidateInit{
		Candidate: "candidate:" + sdpBody,
	}
	if mid != "" {
		m := mid
		init.SDPMid = &m
	}
	if n, err := strconv.Atoi(mid); err == nil && n >= 0 && n <= 0xffff {
		idx := uint16(n)
		init.SDPMLineIndex = &idx
	}
	return init, nil
}

// initiator/responder stay unset; Session stamps them per role before send
func buildTransportInfo(sid, mid, ufrag, pwd, creator string, cand *Candidate) *JingleIQ {
	return &JingleIQ{
		Action: ActionTransportInfo,
		SID:    sid,
		Contents: []Content{{
			Creator: creator,
			Name:    mid,
			Transport: &Transport{
				Ufrag:      ufrag,
				Pwd:        pwd,
				Candidates: []Candidate{*cand},
			},
		}},
	}
}